Trapping and Reservoir Formation Structural and Stratigraphic Traps The accumulation of oil requires a precise geological trap. The movement continues until the oil encounters a non-porous cap rock, such as shale or salt, which acts as a seal.
How Oil Migrates and Gets Trapped Deep Underground
Migration: The Journey Toward Reservoir Rocks Once formed, the newly created oil is not static. Buoyant and less dense than the surrounding rock and water, it begins to migrate upward through porous and permeable geological formations.
Stratigraphic traps form due to changes in rock type, where a porous, oil-bearing layer pinches out against an impermeable layer, effectively sealing the hydrocarbons in place. This journey is often guided by geological structures such as faults or porous rock layers.
How Oil Migrates and Gets Trapped Underground
These traps are the critical final step in concentrating oil into discoverable reservoirs. For stubborn reserves, tertiary recovery techniques such as steam injection or chemical flooding reduce the viscosity of the oil, allowing it to flow more easily to the wellhead.
More About How is oil made in the earth
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